In this section we analyze the strategies of actors protecting their investments with copyleft licenses. Therefore we give an explanation of who the actors are and what investments they own. In section~\ref{ActorExamples} we present three major software projects. Among them is a commercial company, a classical FLOSS project and a Linux distribution which all have different strategies of protecting their code from being used in unauthorized ways.

In the field of FLOSS we define \emph{actor} as the set of people who are involved in a specific (software) project. This does not necessarily contains only software developers. Also the testers, the investors, the lawyers and many more belong to a project and they all have an impact on it. In general all involved people share the common goal to expand the project. Together they \emph{act} as representatives for the project.

In addition to the definition of actor we define \emph{investment} as the related project the actor belongs to. The term \emph{investment} fits quite well because each of the actors has invested either time, money or both into the project. The term becomes more intuitive by specifying a value for the project. For example the value of Linux Kernel in 2010 was estimated to be \EUR{1\,025\,553\,430} \cite{linuxKernel}. It is quite obvious, that it is in the sense of the actors that this investment needs to be protected against exploitation.

By \emph{protection} we understand the set of mechanisms to make sure that the software is used in the sense of the author. The natural protection mechanism is copyright law, which we already introduced in section~\ref{copyright}. In the field of FLOSS it is necessary to define which rights need to be granted to the users of the software. This has initially been done by the definition of the \emph{Four Freedoms}. Copyleft licenses commonly grant the \emph{Four Freedoms}, which we already introduced in the previous section.

The last term we define is \emph{strategy}. In the definition of \emph{strategy} we concentrate on the measures of protection. All in all a \emph{strategy} is the set of used protection mechanisms and an explanation how they are used to protect \emph{all} parts of the related FLOSS project.

\subsection{Examples for Actors and their Strategies using Copyleft Licenses} \label{ActorExamples}
After defining the terms \emph{actors, investments, protection} and \emph{strategies}, we finally can analyze the used protection mechanisms of three major FLOSS projects. We have chosen three different projects, different in the way of their doctrines and overall motivations. More specifically we have chosen the GNU Compiler Collection (GCC) as a representative for one the first FLOSS projects. Second, we have analyzed a commercial company called SugarCRM. Finally, we have analyzed Gentoo Linux because of their usage of copyleft licenses for their project documentation. During our research we noticed, that there are several strategies which all three projects have in common. We describe these common strategies in section~\ref{CommonStrategies}.

\subsubsection{GNU Compiler Collection (GCC)}
The first project we mention is the GNU Compiler Collection (GCC). The GNU Compiler Collection was initially released in 1987 and has been maintained by Richard Stallman. Since not everyone is familiar with the term \emph{compiler}, we give a brief summary of what a compiler is. This is necessary to understand the importance of the growth of this project.

A compiler is a Software which transforms human written source code, mostly written in \emph{higher level programming languages}, into machine executable binary code\footnote{Compilers does not necessarily transforms code from a high-level into a low-level language, but this is the most widely used case.}. Every written software needs to be \emph{compiled} so that it can run on a computer\footnote{There are ways circumvent the use of a compiler for example using a interpreter.}. In 1987 there was already a small marked for \emph{compilers} and programming environments. The marked was mostly covered by firms like Borland\footnote{\url{http://www.borland.com/}} which had very expensive license models for their tools. 

The growth of the GCC has played an imported role in the growth of free software. The biggest difference between the existing compilers was the license model. While Borland has sold their compiler for up to 1000 \$ per license the usage of the GCC was free of charge. The GCC was originally protected by a predecessor of the GNU GPL called the GCC GPL \cite{gccGPL}. Later in 1991 the license changed to the GNU GPL v2. This has been important because with the free use of the software, dedicated programmers got the opportunity to develop software without paying for expensive compiler licenses. Today the gcc is one of the most used compiling tools in the world.

The GCC developers have not changed their strategy of protecting their source code at all. They are still using a copyleft licenses to guarantee the freedom of the software. One important variation is the strategy of how they defend their rights in court. The Free Software Foundation (FSF) represents the GCC project in court. Therefore it is necessary, that the Free Software Foundation holds the copyright of the software, because the lawyers of the Free Software Foundation got the best position, if they can act as a representative of the project \cite{fsfWhyAssign}. A second aspect of this is that the Free Software Foundation can only defend the software, if they own the copyright, more specifically: they can't enforce the law if they were not the owner of the product. 

All together it seems a bit strange that the only way to protect the freedom of the Software is by assigning the copyright to a third person. But if you have a look at the other options, assigning the copyright to the Free Software Foundation is probably be the best way to protect the freedom of the software. Basically the maintainers of the GCC project got two other options. They can use a less restrictive license, which seems to be more free in the first moment, \emph{or} they can use a more restrictive license, which seems to be more protective. Actually both options have major disadvantages. If they would use a less restrictive license, or if they would put it in the public domain, the \emph{Four Freedoms} would still be guaranteed, but they can not prevent anyone from taking the software, modifying it and then selling it, which is not in the sense of \emph{free software}, because with this license model the free GCC would not necessarily stay free in the future. 

Using a more restrictive license also leads to major disadvantages. The most problematic aspect is, that the \emph{Four Freedoms} would probably not be guaranteed. This would have had a huge impact on the development of the GCC and on the development of free software, because without a free (in the sense of freedom) tool for software development, there would not be that many free software project as we have today.

In summary the development of the GCC has played an important role on the growth of the development of free software. Today the GCC is protected by a copyleft license and the Free Software Foundation acts as a representative of the GCC project to defend the freedom of the software in court.

\subsubsection{SugarCRM}

The second actor we mention is SugarCRM. SugarCRM is a commercial software company which develops software solutions for customer relationship management. SugarCRM is a perfect example, that commercial software development and free software are not mutually exclusive. The main idea of the business concept of SugarCRM is the development of a free (in the sense of freedom) community edition of their CRM software and to offer an upgrade of the software with additional non-free features. Therefore SugarCRM trades four commercial editions with additional features and and different license fees \cite{SugarCRMLicense}.

The community edition of SugarCRM is protected by the AGLP, which we already mentioned in section~\ref{AGPL}. The AGPL works quite well for SugarCRM, because with its license they enforce, that all changes made to the software need to be published if the modified software is sold or published. This is already covered by the GPL. Additionally it is prohibited to provide the functionality of the modified software as a web service, when the changes are not published. As copyright holder SugarCRM is solely allowed to sell modified versions without publishing their source code \cite{gnuGPLfaq}. 

The major difference between the strategy of SugarCRM and the GCC is the way of how the copyright is managed. While the Free Software Foundation holds the copyright of the GCC, the copyright for the  SugarCRM software is held by SugarCRM company. This becomes quite important if there is a volunteer who improves the SugarCRM community edition because the copyright of every contribution to the main SugarCRM software tree needs to be transferred to the SugarCRM company. This is necessary because otherwise SugarCRM cannot sell there enterprise products because they would violate the AGPL license of their community edition.

Because of the obligation to assign the copyright of a contribution to a commercial company, there are less voluntary contributors than in other free software projects. But the main advantage for the SugarCRM company is, that they can employ software developers and maintain a free community edition of their software. With the decision to offer a free community edition, they covered the marked, so that there is no need to develop another free CRM solution and even if there would be a fork of there product, they can compete because of their funds and there employed software developers.

All together SugarCRM is a commercial software developing company which protects their investments with a more restrictive AGLP license. As the holder of the copyright, SugarCRM is the only company who can develop enterprise editions for sale without disclosing their source code. With the copyleft license on their community edition, the users of the software can be sure, that it will be free in the future and that there is no motivation to develop another free CRM software.
\subsubsection{Gentoo Linux}

The last actor we present is Gentoo Linux. Gentoo Linux is a Linux distribution for advanced users. The main difference to other distribution is the way of how the available software is provided. Whereas in most of the other distributions\footnote{And also in MacOSX and Windows} the software is pre build, so that it is possible to download an executable file and install it, in Gentoo Linux software needs to be compiled from the source code.

We have chosen Gentoo Linux as an example to show that not only the source code of a project needs to be protected. Of course the source code of Gentoo Linux is protected by a copyleft license (GPL) \cite{gentooLicense}. But as important as the protection of the source code is the protection of the documentation. This becomes even more important if the use of the product relies on a good documentation, because without the documentation the whole product will probably be useless. That is why Gentoo Linux decided to puts their documentation under a Creative Commons copyleft license. They are using Creative Commons Attribution-ShareAlike to make sure, that the documentation stays free. This gives the user the assurance, that even in the case of an unfriendly takeover of Gentoo Linux, the software can be used for any purpose.
\subsection{Common Strategies of protecting Investments} \label{CommonStrategies}
In addition to the individual strategies of the presented actors there are other strategies which all got in common. Some of them may not only apply to copyleft licenses --- for example the defence against unfriendly takeovers. Nevertheless we give a brief summary of these common strategies to protect the freedom of software.

\begin{description}
\item[Source Code in the Public Domain] Almost every actor prevents to have major parts of the source code in the public domain, because in case of a GPL violation it is more difficult to fight against the violation in court. That is why the Free Software Foundation encourages the developers to put only small pieces of code in the public domain \cite{gnuGPLfaq}.

\item[Unfriendly Takeovers] Since a FLOSS project has a specific value on the marked, there will always be a conflict of interest between competing projects, companies and other stakeholders. A copyleft license ensures that the software will be free, even in a case of an unfriendly takeover. Although the copyright management may change, but the copyleft licence is still valid.

\item[Gather Copyright] Because of upcoming difficulties in court if there were many copyright holders involved, most projects gather the copyright and assign it to the Free Software Foundation so that they can act as one representative in court.

\item[Higher GPL Versions] Because of minor flaws in the license code of the GPL, most source code is licensed with the annotation ''or higher''. For example the annotation ''GPL v2 or higher'' prevents the user from voiding the licence forever, because the GPL v3 supports options regain a license.

\item[Name and Logo] The name and the logo of popular FLOSS projects are generally not licensed with a copyleft license because of various reasons. Most of the project names and logos are registered trademarks, and the projects wants to prevent the usage of the trademark in a wrong way.
\end{description}

